1. Field of the Invention
The present invention relates to an antenna, more particularly, to an integrated antenna for a portable computer.
2. Description of the Related Art
In recent years, portable wireless communications devices are becoming increasingly popular. Almost all products must have the function of wireless communications. For a portable computer, wireless communications can reduce the connection wires and solve the problem of setting parameters for hardware of the portable computer. To obtain the function of wireless communications, it is necessary to install an antenna on the portable computer. It is important for a portable computer to include a good designed antenna attached to an adequate position thereof.
Referring to FIG. 1, according to U.S. Pat. No. 6,339,400 B1, antennas 11 and 12 are disposed around a display 10 of a portable computer 1. However, at present, the size of the display of the portable computer is becoming large such that not much space are left to accommodate the antenna. Even if there is space for accommodating the antenna, a very long coaxial cable is needed to connect the antenna to a circuit on a main frame of the portable computer. Therefore, the cost and transmission loss will increase. Besides, it is difficult to install the antenna on the peripheral of the display of the portable computer.
Furthermore, a conventional antenna used for a portable computer can be categorized into a slot antenna, a monopole antenna or a dipole antenna. The slot antenna radiates in two directions, and must connect to a ground plane with large area. An open slot antenna has a resonant length equal to quarter-wavelength of the operating frequency. A closed slot antenna has a resonant length equal to half-wavelength of the operating frequency. The monopole antenna must be disposed away from a ground plane and metal plane. The monopole antenna has a resonant length equal to quarter-wavelength of the operating frequency. The dipole antenna must be disposed away from a ground plane and metal plane. The dipole antenna has a resonant length equal to quarter-wavelength of the operating frequency. The difference between the monopole antenna and the dipole antenna is that the dipole antenna must have a ground metal plane corresponding to a radiating metal strip. Therefore, the total length of the dipole antenna is half-wavelength of the operating frequency. It is a big limitation that the monopole antenna and the dipole antenna must be disposed away from the ground plane and metal plane. Besides, it is a serious defect that the above antennas can easily be interfered by the outside circumference.
Therefore, it is necessary to provide an innovative and progressive integrated antenna so as to solve the above problem.
One objective of the present invention is to provide an integrated antenna for a portable computer. The portable computer has a main frame. The integrated antenna comprises a substrate, a first radiating metal strip, a second radiating metal strip, a ground plane, at least one first connecting metal strip and a second connecting metal strip. The substrate has a connecting portion for connecting to the main frame. The first radiating metal strip is used to induce a first resonance, and the second radiating metal strip is used to induce a second resonance. The first connecting metal strip connects the first radiating metal strip and the second radiating metal strip. The second connecting metal strip connects the second radiating metal strip and the ground plane.
The integrated antenna of the invention is mounted to the main frame of the portable computer. The length of a coaxial cable can be reduced. Therefore, the transmission loss and cost can be reduced. Furthermore, the integrated antenna can be easily mounted on the main frame of portable computer.
According to the invention, the integrated antenna can be operated in multi-band, and has high radiation efficiency and stable performance. Additionally, because the first radiating metal strip, the second radiating metal strip and the ground plane are formed on the first surface of the substrate, the integrated antenna can be easily manufactured and there is no the problem for positioning the above elements and the substrate so as to reduce the error of the integrated antenna.